It sounds as bad gas if it ran fine when u changed the gas filter. However it could be a pump. Try to rule it out by wasting all the bad gas change a fuel filter again woth new gas and check to see what happens then
1996 Mustang GT, 17x9 front and 17x10.5 cobra r replica rims, 255/40/17 front 285/40/17 rear at the moment,
o/r x-pipe flow master 40 series dump downs, cai/ram intake, 75mm c&l throttle body and plenum, pi heads and intake swap, msd wires, stock gears, untuned at the moment, no dyno numbers for now.